// calculate the PI

#include <iostream>
#include <math.h>

int main()
{
    double px = 0.0;
    unsigned int max = 10000;

    for (unsigned int i = 0; i < max; i++) {
        double fm = (i + 1) * (i + 1);
        fm = fm * fm;

        px += 90.0 / fm;

        double pxn = sqrt(sqrt(px));

        printf("pi --%u--> %.12f\n", i,pxn);
    }

    return 0;
}